Hitherto, vacuum packaging is known as one of the packaging methods that packages a packaged object such as a foodstuff. Vacuum packaging is performed by accommodating a packaging bag, in which a packaging object is received, in a chamber of a vacuum packaging apparatus, degassing inside the packaging bag by decompressing inside the chamber, and, in this state, sealing a packaged-object filling opening of the packaging bag by heat sealing or the like (for example, see Patent Literature 1).